Needs better sourcing, but

Henry Dreyfuss added crinkle paint to his Royal Quiet De Luxe typewriter design to diffuse reflected light so that typists who worked at their machines all day wouldn't have headaches from the glare reflecting off the fronts of their machines.

Underwood Typewriter Black Matte Paint Wash & Shine Process Clean Restore Luster No Decal Damage by [[Phoenix Typewriter]]

How Duane cleans black matte paint and crinkle finished typewriters: Simple Green and a stiff brush, dry, then finish off by brushing in oil or WD-40 and wiping down.